1. Field of the Invention
The invention relates to a vehicle control apparatus. In particular, this invention relates to a vehicle control apparatus that controls the torque output from an internal combustion engine provided as a motive power source for the travelling of the vehicle, by using the load that acts on the internal combustion engine when an alternator provided for the internal combustion engine generates electricity.
2. Description of the Related Art
In more and more cases, vehicles use internal combustion engines as their motive power sources. When the output from the engine of a vehicle is to be controlled while the vehicle is traveling, the engine output is controlled by adjusting the degree of opening of a throttle valve that adjusts the amount of air taken into the engine. However, since even air is subject to inertia, the intake air amount tends not to immediately change when the degree of opening of the throttle valve is adjusted but to change after a delay following the adjustment of the degree of opening of the throttle valve. Therefore, the actual output of the engine produced when the degree of opening of the throttle valve is adjusted by a driver operating the accelerator pedal, or through an electronic control of the throttle valve, sometimes changes after a delay following change in the degree of opening of the throttle valve.
If the control of the intake air amount is the only control that is used, the actual change in the output of the engine sometimes has a delay in response to change in the degree of opening of the throttle valve. Therefore, in a related-art vehicle control apparatus, the control of the output of engine is supplemented by controlling the amount of electricity generation of an alternator that generates electricity by using torque that is produced as the crankshaft of the engine rotates. That is, since the alternator generates electricity by using torque generated by the engine, the electricity generation of the alternator involves load being given from the alternator to the engine, which can be seen from the viewpoint of the flowing or transmission of force from the alternator to the engine. Therefore, since part of the motive power generated by combustion of fuel in the engine is used for the electricity generation of the alternator, the control of the output of the engine is supplemented by changing the load to the engine through the control of the amount of electricity generation of the alternator in some control apparatuses.
For example, in a control apparatus for an internal combustion engine described in Japanese Patent Application Publication No. 2001-115871 (JP-A-2001-115871), an idling operation of the engine is appropriately controlled by controlling the load to the engine from an alternator that generates electricity by using part of the motive power of the engine, and also controlling the intake air amount of the engine, during the idling operation of the engine. Furthermore, a control apparatus for an internal combustion engine described in Japanese Patent Application Publication No. 2001-115871 (JP-A-2001-115871) is provided with abnormality detection means for detecting abnormality of an alternator, and stops a control of the load from the alternator to the engine if abnormality of the alternator is detected. This substantially avoids the failure to appropriately perform the idling operation of the engine which results from the controlling of the alternator that is performed during an abnormal state of the alternator.
Besides, in an electricity generation amount control apparatus for an electricity generator for a vehicle described in Japanese Patent Application Publication No. 2005-90339 (JP-A-2005-90339), when the speed change ratio of the automatic transmission is to be shifted, the shift shock is reduced by executing a retardation control of the ignition timing of the engine, and when the engine is in a state of low temperature that is equal to or lower than a predetermined temperature, the shift shock is reduced by increasing the amount of electricity generation through prohibition of the ignition timing retardation control, and therefore increasing the load torque provided by the alternator. That is, during the ordinary travelling of the vehicle, the shift shock is reduced by the retardation control of the ignition timing. During the low temperature state where there arises concern for combustion deterioration, the output of the engine that is substantially transmitted from the engine to the automatic transmission is reduced. This restrains the shift shock when the speed change ratio of the automatic transmission is shifted, while restraining deterioration of emissions.
Thus, in the case where the output of the engine is controlled, a more appropriate control can be performed by using not only the control of the degree of opening of the throttle valve but also the control of the load torque of the alternator. However, in the case where the degree of opening of the throttle valve is controlled or the load torque of the alternator is changed according to the torque demanded of the engine, it sometimes happens that not only the output of the engine but also other states of the vehicle are influenced. Therefore, in the case where the output of the engine is controlled by performing a coordinated control combining the control of the load torque of the alternator and another control, there is a need not to perform the control on the basis of only the output of the engine but to appropriately perform the control by taking into account other conditions as well.